wstar's Journal

wstar

So, I went back to EngineLogics to run on their dyno yesterday. For reference, my previous dyno run was around 15K miles ago. Background from then: I already had Stillen's Gen3 intakes and short headers, Berk HFCs, and Stillen's catback at the time, which is a pretty complete bolt-on setup, and I made right at 300hp even at peak. EngineLogics' dyno is a DynoDynamics, they keep it calibrated really well, and it's known for reading lower than just about any other dyno in town.

Since then I had only made a couple of very small changes that would maybe affect a dyno run by a small amount: an underdriven lightweight crank pulley, and a lighter wheel/tire setup (oh, and swapping a leaky and mangled Stillen catback for Fast Intentions). I was expecting all along that those wouldn't make much difference.

More recently, the dyno-affecting changes have been the M370 intake manifold and a canned tune from UpRev. This dyno trip was mostly about validating where the car's at right now, making sure it wasn't running dangerously lean, etc, before I put on FI's long tube headers (coming in ~6 weeks) and then give it a proper dyno tune.

The results were crappy. The first few pulls were peaking around 280hp, which is a 6.7% drop in peak horsepower. They had my old data to overlay with the new, and it wasn't just a small shift at peak. The graphs overlaid almost perfectly in the lower RPM ranges (which to me, validates that the dyno is still calibrated the same, any weather difference isn't a huge factor, etc), but in the upper RPM ranges the whole curve of the torque and horsepower looked worse than my older data.

Their first comment on the comparative data was that I seemed to be running a lot leaner in the upper RPM ranges than I was before at WOT (we're talking high 12's vs mid 13's AFR, nothing excessively dangerous). The tech said he suspected the canned UpRev tune caused that change, so we map-switched back to the stock tune and did another pull. The AFRs got a bit richer again, and some of the lost power was restored, presumably because our ECU is smart enough to use a bit more timing with a richer mix? In any case, it's not all that shocking that a canned tune sucks, I always knew I'd need a dyno tune once I got done with the engine's breathing setup.

Then we looked closer at the overlay of the old and new torque curves (using the stock ecu map pull). Again identical over the lower RPM ranges, but around the 5K mark is where they diverge. The old graph was smooth, the new one took a couple slow nosedives at different points, and was lower all around in the 5K+ range.

Their theory on this was it *might* be an effect of the intake manifold swap, said they had seen similar results from poorly matched aftermarket intake manifolds/spacers/etc in the past, just due to changes in air turbulence patterns and/or the MAP sensor (which with the M370, gets relocated off of the main manifold body and attached to a vacuum hose off the side, which is something that bugged me a little in the back of my head to begin with, but I figured they must know what they're doing. Still, MAP sensor on a flexible hose? That has to change the timing and magnitude of its response right?).

So I'm back to running on my stock ecu map for now, and after I got back from the dyno last night I swapped back to my stock intake manifold (and re-did some hose work on my oil catch can setup to make it work with the stock manifold (basically like I mentioned in that thread: capping off one of the stock PCV vacuum intakes on the manifold and sending the can's output to the other). I'm planning to head back to EngineLogics for another dyno as soon as they can slot me in, maybe today if I'm super lucky, otherwise probably Monday, and I'll see about getting some printouts of the comparative graphs from my car to post up here if we see anything interesting.

At this point I expect we'll see better numbers without the M370, but it's also possible the remaining loss was just that the engine hadn't re-learned fuel trims, etc from switching back to the stock ecu map? Also keep in mind these results are of course specific to my car's setup, I've seen what looked like good graphs from M370s on others' cars posted here. It may be that the effects of the manifold are highly dependent on the rest of the intake/exhaust setup.

Also, it could be some other wear and tear on my car causing the higher-rpm torque loss. I did check for exhaust leaks when I got home (with a soapwater spray bottle at the flanges, idling cold), didn't see any problems there. Once I get it re-dyno'd back on the stock manifold I should be able to put the M370 issue to rest for my setup though.

RCZ: I should've paid more attention to your doubts than all the other data I was trying to aggregate from the M370 thread, it seems We'll find out soon.

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ChrisSlicks

Interesting. I would have expected a slight peak loss for a little more area under the curve in the mid range, but from what you describe you saw only losses. Leaning out at the high rpm's is never a good thing. Will be watching for your follow up results.

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Hotchkis ARB | Stillen CAI | Art Pipes | Berk CBE | Stillen AP Racing Brakes | AE Performance Oil Cooler | BC Racing ER Coilovers | Doran Control Arms

RockStarKick

In for more results, nice review !!

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2013 Mustang GT, 6M, Track Pack & Leather Recaros
2011 Pearl White 6M /Sport Pkg - SOLD